The thalamic relay to neocortex is dynamically gated. The inhibitory interneuron, which we have studied in the lateral geniculate nucleus, is important to this process. In addition to axonal outputs, these cells have dendritic terminals that are both presynaptic and postsynaptic. Even with action potentials blocked, activation of ionotropic and metabotropic glutamate receptors on these terminal...

Endocannabinoids are lipid retrograde messengers that can be released by postsynaptic depolarization and/or activation of certain metabotropic receptors. We review a recent report that activation of metabotropic 5-HT2 receptors by endogenous serotonin induces the release of endocannabinoids in the olivary nucleus and suppresses glutamatergic input through a presynaptic action. This serotonin-en...

Recombinant protein segments from a metabotropic glutamate receptor and from an odorant receptor were used as substrates in protein kinase C phosphorylation assays. Protein kinase Cβ and δ phosphorylated an intracellular consensus phosphorylation site in the metabotropic glutamate receptor. Only protein kinase Cδ phosphorylated a novel extracellular consensus phosphorylation site in the odorant...

Endocannabinoids are lipid retrograde messengers that can be released by postsynaptic depolarization and/or activation of certain metabotropic receptors. We review a recent report that activation of metabotropic 5-HT2 receptors by endogenous serotonin induces the release of endocannabinoids in the olivary nucleus and suppresses glutamatergic input through a presynaptic action. This serotonin– e...

Neurotransmitter receptors that increase phosphatidylinositol hydrolysis generate second messengers that activate protein kinase C. Here, we used metabotropic glutamate receptor agonists to increase both phosphatidylinositol hydrolysis and secretion of the soluble extracellular fragment of amyloid precursor protein (APPs) from cortical astrocyte cultures. The increase in APPs secretion was mimi...

K+ depolarization or addition of glutamate to a synaptoneurosome preparation triggers a rapid increase in size of polyribosomal aggregates isolated by centrifugation of lysate through 1 M sucrose. The profile of response to the glutamate analogues quisqualate, ibotenate, and 1-aminocyclopentane-1,3-dicarboxylate corresponds to that of metabotropic receptors. Glutamate stimulation is mimicked by...

Kainate receptors signal through both ionotropic and metabotropic pathways. The high-affinity subunits, GluK4 and GluK5, are unique among the five receptor subunits, as they do not form homomeric receptors but modify the properties of heteromeric assemblies. Disruption of the Grik4 gene locus resulted in a significant reduction in synaptic kainate receptor currents. Moreover, ablation of GluK4 ...